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Microdomains and microdomain patterns have been recorded by applying dc voltages to the probe of an atomic force microscope contacting the nonpolar surface in a barium-strontium niobate ferroelectric crystal. Processes of the formation of microdomains have been investigated. It has been shown that the frontal growth of domains on the nonpolar surface is described by a viscous-friction-type law. The features of the formation of stable domains associated with the back-switching effects have been revealed. Oppositely oriented domains ('head-to-head' and 'tail-to-tail') have been obtained in polydomain crystals. Domain gratings with the reciprocal vector G = 2Π/Λ (where Λ = 3.6 and 8 μm is the grating period), which is parallel and perpendicular to the polar Z axis, have been written by the vector lithography method. Gratings with G | Z, which form a system of 180° linear domains of opposite signs (head to head and tail to tail), hold for no less than several days. [ABSTRACT FROM AUTHOR]

Effects of elastic coupling between a ferroelectric thick film and a supporting substrate or underlayer with finite thickness on the apparent longitudinal piezoelectric coefficients are analysed in this work. General analytical solutions of the effective d33 converse piezoelectric coefficients of a film-substrate couple are given as a function of the electromechanical properties, crystalline structure and orientation, as well as the thickness ratio of the couple. Computations of effective d33 coefficients as a function of the thickness ratio are performed for typical tetragonal and rhombohedral lead zirconate titanate ferroelectric films with a composition near its morphotropic phase boundary. These results are compared with those for thin films with the same compositions, where the substrate clamping effect is dominant. [ABSTRACT FROM AUTHOR]

The polycrystalline BaSrGdTiVO, a member of tungsten bronze structural family, was prepared by a solid-state reaction method at high temperature (calcination and sintering temperatures at 950 and 1,000 °C, respectively). Preliminary structural study showed that the compound has orthorhombic crystal structure at room temperature. Study of surface morphology of the compound by scanning electron microscopy exhibits the uniform grain distribution on the surface of the sample with less number of voids. The dielectric anomaly observed at 313 °C is considered as a ferroelectric-paraelectric phase transition temperature which has been confirmed by appearance of hysteresis loop at room temperature. The trend of variation of ac conductivity with inverse of absolute temperature provides the nature of conduction mechanism in the material. The different value of activation energy in different temperature regions suggests that the conduction process in the material is of mixed-type (i.e., ionic-polaronic and space charge due to the oxygen ion vacancies). [ABSTRACT FROM AUTHOR]

Tetragonal PbTiO3-BiFeO3 exhibits a strong negative thermal expansion in the PbTiO3-based ferroelectrics that consist of one branch in the family of negative thermal expansion materials. Its strong negative thermal expansion is much weakened, and then unusually transforms into positive thermal expansion as the particle size is slightly reduced. This transformation is a new phenomenon in the negative termal expansion materials. The detailed structure, temperature dependence of unit cell volume, and lattice dynamics of PbTiO3-BiFeO3 samples were studied by means of high-energy synchrotron powder diffraction and Raman spectroscopy. Such unusual transformation from strong negative to positive thermal expansion is highly associated with ferroelectricity weakening. An interesting zero thermal expansion is achieved in a wide temperature range (30-500 °C) by adjusting particle size due to the negative-to-positive transformation character. The present study provides a useful method to control the negative thermal expansion not only for ferroelectrics but also for those functional materials such as magnetics and superconductors. [ABSTRACT FROM AUTHOR]

Molecular ferroelectrics are highly desirable for their easy and environmentally friendly processing, light weight, and mechanical flexibility. We found that diisopropylammonium bromide (DIPAB), a molecular crystal processed from aqueous solution, is a ferroelectric with a spontaneous polarization of 23 microcoulombs per square centimeter [close to that of barium titanate (BTO)], high Curie temperature of 426 kelvin (above that of BTO), large dielectric constant, and low dielectric loss. DIPAB exhibits good piezoelectric response and well-defined ferroelectric domains. These attributes make it a molecular alternative to perovskite ferroelectrics and ferroelectric polymers in sensing, actuation, data storage, electro-optics, and molecular or flexible electronics. [ABSTRACT FROM AUTHOR]

Bismuth titanate ( Bi4Ti3O12) ( BiT), glass is prepared by the melt-quench technique in the SiO2- K2O- Bi2O3- TiO2 ( SKBT) system doping with Eu2O3 and transparent BiT glass-ceramics ( GC) is derived from it by controlled heat-treatment at 500°C by varying duration. The structural properties of the heat-treated GC are investigated using X-ray diffraction ( XRD), electron microscopy [Field emission scanning electron microscopy ( FE-SEM), transmission electron microscopy ( TEM)], and fourier transform infrared reflectance spectroscopy. FE-SEM and TEM images show the formation of polycrystalline spherical particles of 100-200 nm with 10-15 nm crystallites after heat-treatment. A significant increase in εr value (from 20 to 35) was observed with increase in heat-treatment time. The transmission losses of GC which happened with heat-treatment time are due to Rayleigh scattering exhibited by nanocrystallites of BiT. The excitation spectra have been recorded by monitoring emission at 612 nm corresponding to the 5D0 → 7F2 transition and an intense 467 nm excitation band corresponding to the 7F0 → 5D2 has been observed. Emission spectra were recorded by exciting the glass samples at 467 nm. It is observed that with increase in heat-treatment time, the intensity of red emission at 612 nm increases by 8-fold, which has happened due to the occupancy of Eu3+ ions in the low phonon energy crystal sites of BiT. [ABSTRACT FROM AUTHOR]

The electrocaloric effect in the blends of poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) with small amount of poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) is investigated. It was found that small amount of P(VDF-TrFE) (∼10 wt. %) can cause a more than 10% increase in the crystallinity in the blends. Although the two polymers form separate crystalline phases, the interfacial couplings to the random defects in the terpolymer convert the normal ferroelectric P(VDF-TrFE) into a relaxor ferroelectric. As a result, the blends with 10 wt. % of P(VDF-TrFE) exhibit a 30% increase in the adiabatic temperature change over the entire experimental temperature range (20 °C-60 °C). [ABSTRACT FROM AUTHOR]

In this work, we propose to study the magnetic and ferroelectric configurations in ferroelectric multidomain BiFeO3 single crystals. Using x-ray (magnetic) linear dichroism in a photoemission electron microscope (X-PEEM), we are able to directly image both the antiferromagnetic and ferroelectric domains. We find that inside one single ferroelectric domain several antiferromagnetic domains coexist. This is different from what was observed on epitaxial thin films, where the ferroelectric domains perfectly match the antiferromagnetic ones, but also from previous neutron measurements on ferroelectric monodomain single-crystals for which one single antiferromagnetic domain was identified. This underlines the fundamental differences between thin films, bulk samples, and single versus ferroelectric multidomain samples. [ABSTRACT FROM AUTHOR]

Lead-free piezoelectric (1- x)( Bi0.5(Na0.75K0.25)0.5TiO3)- xBiAlO3 ( BNKT25- xBA, x = 0-0.100) ceramics were synthesized using a conventional solid-state reaction method. The effect of BA addition into the BNKT25 ceramics was investigated by X-ray diffraction, dielectric and ferroelectric characterizations, and electric field-induced strain. X-ray diffraction revealed a phase transition from a tetragonal to a pseudocubic phase at x = 0.050. As the BA content increased, the maximum dielectric constant as well as the depolarization temperature ( Td) decreased. The polarization and strain hysteresis loops indicate that the addition of BA significantly disrupts the ferroelectric order of the BNKT25 ceramics leading to a degradation of the remanent polarization and coercive field. However, the destabilization of the ferroelectric order is accompanied by a significant enhancement in the unipolar strain which peaks at x = 0.025 with a value of ~0.29%, which corresponds to a normalized strain, d *33 (= Smax/ Emax) of 484 pm/V. It was observed that the unipolar strain of 0.025 xBA is fairly temperature-insensitive up to 150°C, even at 130°C the d*33 is as large as ~415 pm/V. [ABSTRACT FROM AUTHOR]

It is experimentally observed that PNN-PT ceramics processed with glycerol possess superior unipolar fatigue resistance; but the same ceramics processed without glycerol are vulnerable to unipolar fatigue. For PNN-PT-glycerol fatigued by 5×107 unipolar cycles, there are no losses in the maximum polarization (Pmax) and remnant polarization (Pr). But for PNN-PT, these losses are B14% and 22%, respectively. In addition, strain asymmetrycS and internal bias field Ebias of PNN-PT-glycerol are much less than those of PNN-PT. However, the ferroelectric properties can be recovered by bipolar cycles and thermal annealing; and such recovery is much easier and larger in PNN-PT-glycerol than in PNN-PT ceramics. Scanning electron microscopy micrographs show that the significant loss in properties of the fatigued PNN-PT ceramics is accompanied by a measurable number of severely damaged grains in the samples, especially in the region near the electrode surface, whereas the much less damaged grains in the PNN-PT-glycerol ceramics contribute to their good fatigue performance. [ABSTRACT FROM AUTHOR]

Much attention is drawn to the fundamental research and the applications of the relaxor-based ferroelectrics for the next generation of piezoelectric devices. Mass production of Pb(Mg1/3Nb2/3)O3- xPbTiO3 (PMNT) and ternary xPb(In1/2Nb1/2)O3- yPb(Mg1/3Nb2/3)O3- zPbTiO3 (PIMNT) single crystals with a Bridgman method was reported. The piezoelectric, pyroelectric, and electric-optical performances of PMNT single crystals are much more excellent than traditional ceramics with the composition near morphotropic phase boundaries. Compared with PMNT crystal, PIMNT crystals can be used in a more broad range of device applications due to their high Curie temperature Tc and large coercive fields Ec. A relaxor-based Na0.5Bi0.5TiO3- xBaTiO3 (NBBT) crystal grown by the top seeded solution growth method was also investigated to find a lead-free material with better piezoelectric performance. The properties of these relaxor-based single crystals were summarized. The mechanism of the enhanced piezoelectric response is discussed, based on the phase transitions induced by the variations of the temperature, pressure, composition, and electric field. [ABSTRACT FROM AUTHOR]

The electro-mechanical behavior of ferroelectric materials is studied by a joint experimental and numerical investigation. The experiments were performed on lead zirconate titanate PIC151 (PI Ceramics) samples, and the numerical simulations were done by a 2D Finite Element implementation of a continuum phase field model. To limit computational costs, the material is idealized as a single crystal. The phase field parameters for the material are determined through experimental parameter identification. Numerical results are presented to show the domain structure evolution within the crystal. In comparison to experimental results, calculations are carried out to disclose mesoscopic properties of the material under various poling scenarios, the dependence of the coercive field on the electric loading frequency, and the improvement of the material properties by stress-assisted poling procedures. [ABSTRACT FROM AUTHOR]

Nanocrystalline powders of the composition Pb(Zr0.52Ti0.48)O3 were obtained by Mechanical alloying (high-energy ball milling). X-ray diffraction studies show that these compounds are completely into the perovskite phase. Detailed studies of electrical and mechanical properties of PZT as a function of temperature (and frequency) showed the high permittivity of 20653 at Curie transition temperature. Temperature variation of longitudinal modulus and internal friction of these ceramics at 104 kHz frequency were studied in the wide temperature range of 30°C-420°C. The internal friction measurements showed sharp stress induced relaxation peaks in the present composition corresponding to those temperatures where the minima were noticed in temperature variation of longitudinal modulus behavior. This dielectric and internal friction behaviour was explained in the light of polaron hopping mechanism and structural phase transitions in the present piezoelectric compositions. [ABSTRACT FROM AUTHOR]

Multilayers consisting of alternating ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer and relaxor poly(vinylidene fluoride-trifluoroethylene-chlorofloroethylene) (P(VDF-TrFE-CFE)) terpolymer with different periodicities in thickness were prepared. A superlattice-like structure is shown in the polymer multilayer as the periodic thickness is lower than a critical value. The dielectric constant of the multilayer with a small periodic thickness is two times higher than that of the P(VDF-TrFE) copolymer over a temperature range between 300K and 350K. The multilayer also shows a good ferroelectricity in the same temperature range. The enhanced electrical properties of the multilayers are due to the long-range ferroelectric coupling. [ABSTRACT FROM AUTHOR]

Giant electro-mechanical energy conversion is demonstrated under a ferroelectric/ferroelectric phase transformation in [011] cut and poled lead titanate-based relaxor perovskite morphotropic single crystals. It is found that under mechanical pre-stress, a relatively small oscillatory stress drives the material reversibly between rhombohedral and orthorhombic phases with a remarkably high polarization and strain jump induced at zero bias electric field and room temperature. The measured electrical output per cycle is more than an order of magnitude larger than that reported for linear piezoelectric materials. Ideal thermodynamic cycles are presented for this electro-mechanical energy conversion followed by a presentation and discussion of the experimental data. [ABSTRACT FROM AUTHOR]

We report direct observation for the structural transformations of relaxor ferroelectric Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals with the aid of temperature-dependent polarized Raman scattering and X-ray diffraction. The cubic to tetragonal phase transition is observed at 460 K and tetragonal to rhombohedral structural transformation takes place at 390 K, which are consistent with the results determined by dielectric spectroscopy. In addition to two well-known phase transitions above room temperature, anomalous structure deformations involving octahedral rotations and tilting angle of polarization can be found around 200 K. A comparison of experimental results with the Devonshire expansion of the free energy by Vanderbilt et al. [Phys. Rev. B 63, 094108 (2001)] allows us to elucidate the peculiar characteristic as the variation of volume fractions among coexistence of three phases, including a first-order phase transition between the orthorhombic and rhombohedral phases and a second-order phase transition between the monoclinic and orthorhombic ones at low temperature. [ABSTRACT FROM AUTHOR]

Inhomogeneity in ferroelectrics can exist as undesirable defects in the single crystalline structure or as designable factors in the composite structure. Surface or interface is inhomogeneous in nature, and superlattices or mixed-phases are inhomogeneous under plan. Effects of the inhomogeneous interfacial layer on ferroelectric nonlinearity have been investigated using a time-dependent Ginzburg-Landau model based on phenomenological equation for a two-dimensional lattice of ferroelectric unit cells. The simulation is based on Ba0.8Sr0.2TiO3 (BST) with and without the inhomogeneous interfacial layer, e.g., nonswitchable fixed dielectric, switchable linear dielectric, or switchable nonlinear dielectric, and with and without Ginzburg-type gradient effect originated from the interactions between the BST and interfacial layers. Homogenization of the inhomogeneous systems is realized by the gradient effect allowing the gradual variation in polarization between the neighboring unit cells, and it heavily depends on the dielectric type of the interfacial layer-whether or not the gradient effect is applied to the interfacial layer. Effects of frequency, electric field type, depolarization, lattice strain, temperature, and thickness on the inhomogeneous nonlinearity are discussed. [ABSTRACT FROM AUTHOR]

Mn doped PbZr0.52Ti0.48O3 (PZT) thick films with highly (100) preferential orientation have been prepared by chemical solution deposition according to doping concentration of 0, 0.5, 1, 2, and 3 mol. %. The effect of Mn-doping on structures and electrical properties of PZT thick films has been investigated. With increasing Mn doping concentration, the dielectric constant first increases and then decreases. PZT film with 0.5 mol. % Mn doping has a maximum value of 2252 and a dielectric loss of 0.011 at 1 kHz. Mn doping below 3 mol. % could effectively reduce the leakage current density of PZT films. The mechanism of Mn doping on dielectric and ferroelectric properties of PZT thick films has been investigated and discussed. [ABSTRACT FROM AUTHOR]

We report an elastic relaxation and increase in local strain variation correlated with ferroelectric domains within epitaxial BiFeO3 thin film nanostructures fabricated by combined electron-beam and focused ion-beam nanolithography. Nano-focused x-ray diffraction microscopy provided new insights into the relationship between film strain and ferroelectric domains in nanostructures, namely: (i) an out-of-plane (C-axis) elastic relaxation of as much as -1.8% Δc/c in a BFO film-based nanostructure relative to the planar film lattice constant; (ii) an out-of-plane rotation trending from the center towards all released edges of the nanostructure; and (iii) an increase of inter-domain strain variation within the nanostructure of approximately 10 times the inter-domain variation found within the planar film, correlated with ferroelectric domain boundaries as confirmed by piezoresponse-force microscopy. These results indicate that the release of in-plane BFO/SRO mismatch strain in a planar film is taken up by the local ferroelectric domain structure after patterning, resulting in greatly increased mechanical strain gradients within the structure. [ABSTRACT FROM AUTHOR]

In piezoresponse force microscopy a lateral signal at the domain boundaries is occasionally observed. In recent years, a couple of experiments have been reported and varying explanations for the origin of this lateral signal have been proposed. Additionally, elaborated theoretical modeling for this particular issue has been carried out. Here we present experimental data obtained on different crystallographic cuts of LiNbO3, BaTiO3, and KTiOPO4 single crystals. We could thereby rule out some of the explanations proposed so far, introduce another possible mechanism, and quantitatively compare our results to the existing modeling. [ABSTRACT FROM AUTHOR]

The flexoelectric effect, which describes the induction of polarization from strain gradient, is negligible in bulk but not nanometer scale ferroelectrics. The influence of flexoelectric effects on magnetic field induced electric polarizations in multiferroic nanocomposite thin bilayer films has been investigated. It has been found that with flexoelectric effects taken into consideration, the polarization would not be reduced to zero even if the film was ultra-thin. Under an applied magnetic field, polarizations were induced from two effects, i.e., the conventional electrostrictive and flexoelectric effects. In the case where the film thickness was relatively large, the former factor was the main one influencing the magnetic field induced polarization. By decreasing the film thickness, the flexoelectric induced polarization became more and more dominant and it finally overcame the electrostrictive induced polarization and changed the value of magnetic field induced polarization from negative to positive. [ABSTRACT FROM AUTHOR]

Pb(Zn1/3Nb2/3)0.95Ti0.05O3 (PZNT) single crystals with 5 mol. % alkali niobate such as LiNbO3 (LN), NaNbO3 (NN), and KNbO3 (KN) were fabricated by using a flux method to investigate the effect of A-site cation radius on the structure and ferroelectric properties of PZNT under electric field (E-field). Their structure and properties showed different electric field dependence. Polarization versus electric field and strain versus electric field curves of PZNT-0.05LN showed E-field induced phase transition from a relaxor state to a normal ferroelectric state. However, only relaxor behavior was observed in PZNT-0.05NN and PZNT-0.05KN. The effect of A-site ion doping is attributed to the change in local lattice distortion and polar nano-region. When smaller cation such as Li ion substitutes Pb ion, the off-center displacement of Nb ion stabilizes rhombohedral lattice distortion. They, in turn, facilitate the development of macro-domains under electric field (E-field) in PZNT-0.05LN. In contrast, the substitution of Pb with larger cations such as Ni and K decreases the rhombohedral distortion of PZNT, which leads to the disappearance of unique E-field induced phase transition from rhombohedral to tetragonal phase in PZNT. Therefore, non-linear electrostrictive behavior of relaxor ferroelectrics is found in PZNT-0.05NN and PZNT-0.05KN. [ABSTRACT FROM AUTHOR]

In this paper, vertically trapped charge location is investigated to understand the carrier-transport dynamics in chromium-doped strontium titanate (Cr-SrTiO3 (STO))-based charge trapping memory devices using a transient analysis method. The vertical location of trapped charges is found to move from the Cr-SrTiO3/Si3N4 interface to the bulk region of Si3N4 with an increasing of the electric field, and, particularly, available trap sites are limited at the Cr-SrTiO3/Si3N4 interface by hole injection from the Si substrate into the Si3N4 layer at a high electric field (EOX > 7 MV/cm). In addition, some of these charges passing across the SiO2 (OX) layer generate many Si-SiO2 interface traps (Dit: 1.58 × 1012 cm-2 eV-1) that may degrade the device. However, the trapping efficiency can be improved by using sufficiently thick ( > 10 nm) bottom layers and by preventing direct hole tunneling and thereby, reducing the interface trap density. [ABSTRACT FROM AUTHOR]

A discussion is given of ferroelectrics (FEs) that have their Curie temperatures Tc very near absolute zero. These have differences in their dynamics in comparison with higher-temperature systems, since domain wall motion occurs via quantum mechanical tunneling and not by thermally activated diffusion. Emphasis in the present paper is on FEs that have relaxor characteristics. In such systems, the temperature at which the isothermal electric susceptibility ε(T,f) peaks is a strong function of frequency, and it decreases with decreasing frequency. This is due to glassy viscosity and is symbolic of non-equilibrium dynamics, usually described by a Vogel-Fulcher equation. It permits an extra dimension with which to examine the transitions. The second half of this paper reviews domain wall instabilities and asks about their presence in QCP ferroelectrics, which has not yet been reported and may be unobservable due to the absence of thermal diffusion of walls near T = 0; in this respect, we note that diffusion does exist in ferroelectric relaxors, even at T = 0, by virtue of their glassy, viscous dynamics. [ABSTRACT FROM AUTHOR]

The article discusses the techniques in understanding the vortices in ferroelectric manganates. Topics include ferroelectric polarization, the paraelectric phase, and studying the frozen vortex with piezoelectric force microscope. Topological defects and quantum phase transitions are also mentioned.

Crystal structure predictions of Pb0.5Ba0.5TiO3 alloys under different pressures are performed based on the particle swarming optimization algorithm. The predicted stable ground-state and high-pressure phases are tetragonal ferroelectric (I4mm) and cubic para-electric (Fm3̅m), respectively, whose structural details have not been reported. The pressure-induced colossal enhancements in piezoelectric response are associated with the mechanical and dynamical instabilities instead of polarization rotation. The band gap of the tetragonal phase is indirect and that of the cubic phase is always direct. As pressure increases, the alloy displays the similar band-gap behaviors to PbTiO3, while different from BaTiO3, which is attributed to the different orbital contributions to the valence bands. Our calculated results are in good agreement with the available data. [ABSTRACT FROM AUTHOR]

In this letter, we report a lead-free piezoelectric ceramic system (Bi0.5Na0.5)1−xBaxTi0.98 (Fe0.5Sb0.5)0.02O3 which shows a surprisingly high field-induced nonlinear strain of 0.57% comparable to those obtained in Pb-based antiferroelectrics. The ultrahigh strain response of the composition stems from the composition proximity to the ferroelectric-nonpolar phase boundary, which leads to reversible transformation between a nonpolar phase and a polar ferroelectric phase under cyclic fields. In particular, this material is very attractive for its exceptionally good fatigue resistance (up to 106 cycles) and high temperature stability (25–100 °C) due to its stable nonpolar phase and lower defect density. These findings render the current material a great opportunity for novel applications in ultra-large stroke and nonlinear actuators demanding improved cycling and thermal reliabilities. [ABSTRACT FROM AUTHOR]

The atomic-scale response of dielectrics/ferroelectrics to electric fields is central to their functionality. Here we introduce an in situ characterization method that reveals changes in the local atomic structure in polycrystalline materials under fields. The method employs atomic pair distribution functions (PDFs), determined from X-ray total scattering that depends on orientation relative to the applied field, to probe structural changes over length scales from sub-Ångstrom to several nanometres. The PDF is sensitive to local ionic displacements and their short-range order, a key uniqueness relative to other techniques. The method is applied to representative ferroelectrics, BaTiO3 and Na½Bi½TiO3, and dielectric SrTiO3. For Na½Bi½TiO3, the results reveal an abrupt field-induced monoclinic to rhombohedral phase transition, accompanied by ordering of the local Bi displacements and reorientation of the nanoscale ferroelectric domains. For BaTiO3 and SrTiO3, the local/nanoscale structural changes observed in the PDFs are dominated by piezoelectric lattice strain and ionic polarizability, respectively. [ABSTRACT FROM AUTHOR]

In recent years, several papers reported an enhanced dielectric anisotropy when ferroelectric particles were suspended in a liquid crystal. These results seem to be sensitive to the liquid crystal used and the preparation method of the ferroelectric particles. In this paper, we compare different preparation methods of suspended barium titanate in two different liquid crystal hosts. As a control experiment, we followed similar preparation steps with non-ferroelectric silica particles. In all cases, we found a broadening of the optical Frederiks transition but no change in the dielectric anisotropy. Raman spectroscopy has been used to investigate the loss of tetragonal structure in the barium titanate as a function of milling time and particle size. As reported in the earlier literature, barium titanate does not exhibit a well-defined tetragonal crystal structure below a certain particle size and loses its ferroelectric features. This provides a simple rationalization for the absence of any dielectric enhancement. [ABSTRACT FROM AUTHOR]

We demonstrate charge-mediated and non-volatile control of anisotropic magnetoresistance (AMR) in a dilute magnetic semiconductor (Ga,Mn)(As,P) with an integrated polymer ferroelectric gate. The persistent electric field associated with switchable polarization in the ferroelectric layer is shown to be capable of strongly modulating the AMR magnitude. Furthermore, ferroelectric gate switching has a profound impact on the nature of AMR, changing the symmetry of the effect and enhancing/suppressing the crystalline component of AMR. Thus, in addition to a rather weak modulation of the ferromagnetic Curie temperature (4-5 K) reported previously, the ferroelectric gate can induce a strong deterministic switching of the magnetotransport anisotropy. [ABSTRACT FROM AUTHOR]